Software-defined networking (SDN) is an approach to computer networking that allows network administrators to manage network services through abstraction of higher-level functionality. This is done by decoupling the system that makes decisions about where traffic is sent (the control plane) from the underlying systems that forward traffic to the selected destination (the data plane). The control plane communicates with the data plane via the OpenFlow protocol.
A hybrid SDN network utilizes both legacy hardwired switches and software programmable switches that use SDN protocols. This mixed mode of operation is found as service providers migrate legacy networks to SDN technology.
Under the hybrid SDN network; there are problems such as complicated configurations or additional hardware equipments that are required to increase the cost when initializing an existing network application.